1. Field of the Invention
This invention relates to arylalkylsulfonic acids and new and improved processes for the preparation of arylalkylsulfonic acids. These acids can be made from aromatic or substituted aromatic molecules and alpha olefin sulfonic acid (“AOS acid”; generally a mixture of alkenesulfonic acid and sultones, produced from the sulfonation of alpha olefins). More particularly, the invention relates to the use of a superacid catalyst (or an effective alkylation promoter) to effect the reaction of AOS acid and aromatic reactants to produce arylalkylsulfonic acids under substantially anhydrous conditions and to produce cleaning compositions derived therefrom.
2. Description of Related Art
Alkylbenzene sulfonic acids and the corresponding sulfonates (i.e., neutralized sulfonic acid) have found wide spread use as surfactants in a variety of detergent, emulsion and industrial applications. These materials typically comprise a substituted aromatic ring, with an alkyl group at one position on the ring and a sulfonic acid moiety attached to another position on the ring; polyalkylates may also be present. Synthetic detergents based on the reaction of propylene tetramer and benzene using Lewis acid catalysts, such as AlCl3 for example, were once widely used in laundry detergent formulations, but such use has diminished significantly due to environmental concerns. Also used in such formulations, although somewhat less popular, are alkylbenzene sulfonates based on branched alkyl groups. Linear alkylbenzenes starting materials which are based on the reaction of linear olefins (see, e.g., U.S. Pat. No. 3,585,253; to Huang, Jun. 15, 1971) or linear chloroparaffins (see, e.g., U.S. Pat. No. 3,355,508; to Moulden, Nov. 28, 1967) with benzene in the presence of a Lewis Acid catalyst are also well known in the surfactant art. These materials possess excellent detergency properties and are rapidly biodegradable. More recently, HF (or the Detal process variation) has become the alkylation catalyst of choice for the preparation of alkylated benzenes and other alkylated aromatic compounds, based upon environmental objections to the use of AlCl3.
Detergent use is the predominant market for alkylbenzene sulfonates. However, these products are also employed in considerable quantities as additives in lubricants, coolants, industrial surfactant formulations, dispersants, emulsifiers, corrosion inhibitors and demulsifiers. Alkylbenzene sulfonates find widespread use in many industries among which are the petroleum recovery, refining, emulsion polymerization, textile dyeing, agriculture, institutional cleaning, drilling fluids, paper processing, coatings, and adhesives industries.
Present processes for producing alkylaromatics are designed to optimize the yields of detergent alkylate (predominantly monoalkylbenzene). The yields of heavy alkylate (predominantly dialkylbenzene) are therefore low. These heavy alkylates, however, find considerable demand as oil soluble surfactants and specialty chemicals. Dialkylbenzene sulfonates (see, e.g., U.S. Pat. Nos. 4,004,638; to Burdyn, et. al., Jan. 25,1977; 4,536,301; to Malloy, et. al., Aug. 20, 1985), alkyl xylene sulfonates (see, e.g., EP121964) and dialkyl phenol polyethoxy alkyl sulfonates (see, e.g., U.S. Pat. No. 4,220,204; to Hughes, et.al., Sep. 2, 1980) have all been used to increase the productivity of crude oil. Recently, U.S. Pat. No. 6,043,391; to Berger, et. al., Mar. 28, 2000, disclosed new sulfonic acid materials and processes for producing di- and tri-alkylbenzenes where both linear and branched alkyl groups are present on the same benzene ring.
Alkoxylated alkyl substituted phenol sulfonates have been produced and found to be useful as surfactants in numerous applications (see, e.g., U.S. Pat. No. 5,049,311; to Rasheed, et. al., Sep. 17, 1991, listing many uses for these compounds including use in enhanced oil recovery processes, as corrosion inhibitors, hydrotropes, foaming agents in concrete formation, surfactants for dye carriers, surfactants for fiber lubricants, surfactants for emulsion polymerization, as textile detergents, as foaming agents for drilling fluids, and as agricultural emulsifiers).
Alpha-olefin sulfonates (AOS) are widely used as surfactants in personal care, emulsion polymerization and fire-fighting foam applications, as well as a wide variety of other uses. These materials are typically produced on a commercial scale by sulfonating an alpha-olefin with SO3, in a falling film sulfonator (see, e.g., Weil, Stirton and Smith; JOACS Vol 42, October 1965, pp 873-875, describing the reaction of hexadecene-1 and octadecene-1 with SO3 followed by neutralization with NaOH to form the corresponding hexadecene sulfonates). The AOS precursor alpha-olefin sulfonic acid typically comprises alkene sulfonic acid and various sultones. As is well known to those of skill in the art, AOS correspondingly does not comprise a single component, but predominantly a mixture of two materials: an alkene sulfonate and a hydroxyalkane sulfonate. The hydroxyalkane sulfonate is present due to the formation of intermediate sultones when SO3 reacts with the alpha olefin. Neutralization, with NaOH for example, not only neutralizes the alkene sulfonic acid formed during the sulfonation reaction, but also opens the sultone ring forming additional alkene sulfonate and hydroxyalkane sulfonate. Thus, neutralization results in a final product comprising approximately 60-70% alkene sulfonate, approximately 30% 3-, and 4-hydroxy sulfonate and approximately 0-10% disulfonate material; these percentages can vary greatly depending on the sulfonation and neutralization conditions which are utilized.
U.S. Pat. No. 3,845,114, to Sweeney, et. al., Oct. 29, 1974, teaches that the addition of limited amounts of water to alkene sulfonic acid with subsequent heating to 150° C. converts the sultone to alkene sulfonic acid and hydroxyalkane sulfonic acid. The presence of water during the ring-opening prevents dimerization of the alkene sulfonic acid. Removal of the water dehydrates the hydroxyalkane sulfonic acid back to sultone and alkene sulfonic acid, but leaves the already present alkene sulfonic acid intact. Repeating the process of adding limited amounts of water, heating to 150° C. and removing the water reduces the hydroxyalkane sulfonic acid content and increases the alkene sulfonic acid content. This “conversion” process is shown below in Scheme 1. Typically, for example, for a linear alkyl material, a may be an integer from 1 to 3 and b may be an integer from about 10 to 13, giving c+d=10-15. Very recently, U.S. Pat. No. 6,043,391 (“the '391 patent”); to Berger, et. al., Mar. 28, 2000, disclosed sulfonic acid materials and processes for producing such materials which required the use of this water/conversion process for the preparation of such materials. In the '391 patent, crude alkene sulfonic acid (containing significant amounts of sultone) produced from the reaction of an alpha-olefin and SO3, is subjected to the aforementioned water addition and removal process for conversion of sultone to alkene sulfonic acid, which is then used to alkylate a variety of aryl compounds such as benzene, naphthalene, substituted benzene or substituted naphthalene.

Ault, et. al., JOACS, Vol 39, February 1962, pp 132-133, describes the acid catalyzed addition of phenols and phenyl ethers to oleic acid. It was discovered that by using an acid catalyst, such as polyphosphoric acid or methane sulfonic acid, production of aryl substituted stearic acids was possible, as depicted in Scheme 2. Typically, for example, for a linear alkyl material, m+n may equal 14, thus o+p equal 15.

U.S. Pat. No. 3,502,716; to Kite, Mar. 24, 1970, discloses the use of alkali or alkaline earth metal carboxylates reacted at high temperature with hydroxy sulfonic acid anhydrides to produce the corresponding alkali or alkaline earth alkene sulfonate salts.
U.S. Pat. No. 3,951,823; to Straus, et. al., Apr. 20, 1976, teaches the reaction of AOS acid with itself and other sulfonated monomers to produce disulfonated dimers having good foaming properties for use in foam well cleanout applications. The '823 patent specifically requires that both monomers contain a sulfonate group and further teaches that suitable starting materials must contain at least about 5 nonaromatic carbon atoms per molecule, a sulfonate functional group, i.e., —SO3—, and one of the following: (1) a carbon-carbon double bond, i.e., —CH═CH—; (2) an alkanol hydroxy group, or a sulfonate ester group of which the above sulfonate group is a component, i.e., a sultone, and the functional groups must be substituents attached to non-aromatic carbon atoms with the balance being carbon and/or hydrogen.
Also, as general alkene sulfonic acid and aromatic sulfonic acid background, see e.g., U.S. Pat. No. 2,336,113, Suter, C., Dec. 26, 1944, disclosing the condensation of olefin sulfonic acids with aromatic compounds; U.S. Pat. No. 3,845,114, Sweeney, et. al., Oct. 29, 1974 disclosing processes for conversion of sultones to alkene sulfonic acids; U.S. Pat. No. 3,721,707, Straus, et. al., Mar. 20, 1973, describing organic sulfonic acid oligomers and processes for producing same; U.S. Pat. No. 3,873,590, Straus, et. al., Mar. 25, 1972, describing methyl esters of sulfonic acid oligomers; U.S. Pat. No. 3,875,102, Straus, et. al., Apr. 1, 1975, describing use of methyl esters of sulfonic acid oligomers plasticized with polyvinyl chloride; U.S. Pat. No. 3,953,338, Straus, et. al., describing the use of oligomeric sulfonic acids for foam well cleanout; and U.S. Pat. No. 5,034,161, Alink, B. A., Jul. 23, 1991, describing the synthesis of aryl-substituted aliphatic acids.
The forgoing references teach several ways in which alkene sulfonic acid materials can be reacted with aromatic materials to produce derivative sulfonic acid materials. However, to date, prior processes have required the conversion of crude acid from the reaction of an alpha-olefin and SO3, via the repeated hydrolysis and dehydration with water, resulting in the formation of alkene sulfonic acid as taught by U.S. Pat. No. 3,845,114. Such conversion is time consuming, inconvenient, and on a commercial scale, can be quite costly. Additionally, prior alkene sulfonic acid alkylation processes have failed to produce alkylated products with high reaction throughput rates (i.e. yields) and/or high levels of selectivity toward the desired mono-alkylate products, versus undesirable dialkylate and/or AOS acid dimmer/oligomer materials. Typically, prior art processes which attempted to increase selectivity toward mono-alkylate production via the use of excess aromatic compound were not successful and lower rates were typically obtained.
In view of the limitations associated with previously known alkene sulfonic acid processing technologies, a need exists for a superior alkylation process whereby a substantial improvement is realized in terms of the reaction rate and reaction product selectivity. Additionally, there is a need for an alkene sulfonic acid alkylation process which does not require tedious conversion of crude alkene sulfonic acid (i.e., conversion whereby water is added and removed in a cyclic manner (and heating is applied) to and from the crude AOS acid to convert the sultone to alkene sulfonic acid) prior to alkylation. Further, there is a need for an alkene sulfonic acid alkylation process which does not require digestion of the crude alkene sulfonic acid prior to its use in the alkylation process.